UNIX Background

After three decades of use, the UNIX computer operating system from Bell Labs is still regarded as one of the most powerful, versatile, and flexible operating systems (OS) in the computer world. Its popularity is due to many factors, including its ability to run a wide variety of machines, from micros to supercomputers, and its portability -- all of which led to its adoption by many manufacturers.

Like another legendary creature whose name also ends in 'x,' UNIX rose from the ashes of a multi-organizational effort in the early 1960s to develop a dependable timesharing operating system.

The joint effort was not successful, but a few survivors from Bell Labs tried again, and what followed was a system that offers its users a work environment that has been described as "of unusual simplicity, power, and elegance...."

Its development and evolution led to a new philosophy of computing, and it has been a never-ending source of both challenges and joy to programmers around the world.

A Bit of Unix History

Unix was originally developed at AT&T Bell Laboratories (now Lucent Technologies) by Ken Thompson and Dennis Ritchie in 1969-1970 to store information on a computer. The name Unix was coined to give this system a name, not as an acronym or an abbreviation for anything. Bell Labs was the early developer of Unix as an operating system to serve the internal needs of its staff.

In 1973, Unix was rewritten in C, a computer programming language also developed at Bell Labs by Dennis Ritchie. This made it possible for Unix to be installed and run on many different types of computers which had a C compiler. AT&T did not actively market Unix in the 1970's. But Unix was given to universities for research. Researchers at the University of California at Berkeley developed a variant of AT&T's Unix. This variant (or "flavor") is called "Berkeley Unix" or BSD (Berkeley Standard Distribution) Unix, (or, humorously, "Bezerkly Unix"). Other companies, notably AT&T itself, later developed and released commercial versions of Unix. Over time, many flavors of Unix have come and gone. These "flavors" of Unix might not work precisely the same as each other, but they are like dialects or slang speech from the same common tongue. Other operating systems are very close to Unix in concept and syntax. Linux is one. Flavors of Unix run on many different kinds of hardware systems, from personal computers to supercomputers.

The other kind of variation in Unix systems is the type of command interpreters. We will see how Unix is command-driven. You issue a command, something happens, and you keep issuing commands until you get your work done. You issue these commands to a command interpreter. The command interpreter in Unix is called the shell. There are different kinds of shells.